That's just your thought. Valve ruined the hitboxes with their patch to the game which as well brought the Achievements into the game itself.
Same goes for interp, rates and such. Check out phoon's "too much for zBlock" and you'll understand what I'm talking about. Such bhop is impossible nowadays without a script. Figuratively put, all that the server can do is just change the rates and settings regarding the motion of the hitboxes but not fix the actual hitboxes...
I hope I made myself clear and helpful. I apologize in advance if I have not.
Sincerely,
-cHeT [BeWasted]